The present paper deals with the experimentation of a hydrogenated Palm Kernel vegetable fat as a novel bio-based Phase Change Material (PCM). This bio-based PCM with 26.53 °C of melting temperature and 74.35 J/g of the latent heat capacity of fusion was recovered from abundant and renewable underused feedstocks. The purpose is to trap this PCM without leakages into the internal microstructure of a prepared supporting material (matrix) first; and then to propose the resulting composite-PCM for a practical application of passive TES in building envelopes. This matrix was prepared from available, low-cost and eco-friendly components. However, natural clay and cellulose fibers were principally used in the preparation of the PCMs’ supporting material. 53 wt percent (wt%) of the bio-based PCM were successfully incorporated in this matrix after the direct immersion method thanks to the capillary and surface tension forces. Differential Scanning Calorimetry (DSC) results showed that the Thermal energy storage characteristics of the obtained composite-PCM are suitable for building applications. This melts at 27.33 °C with 40.27 J/g of latent heat capacity of fusion. Thermo Gravimetric Analysis (TGA) revealed that the prepared composite-PCM maintains a good thermal reliability in its working temperature range. The Hot-Disk results proved that the addition of graphite improved its thermal conductivity. Fourier Transformed Infrared Spectroscopy (FT-IR) confirmed the chemical stability of the prepared material. Finally, Scanning Electron Microcopy (SEM) showed that the bio-based PCM is successfully retained by the microstructure of the prepared matrix after the impregnation process.